car ran rough when first starting,now wont start

Turn over but not start? If so check fuses and also check fuel pressure on fuel rail.

You don't say that it does or doesn't turn over. We need much more info to trouble shoot this one. Does it turn over? Does it try to fire? Does it run at all, rough or otherwise? give more info

It does turn over, just wont start at all.

OK...Now to start. You haven't filled out your profile so I have no idea what year your Expo is or what engine it has. I'm just going to have to make some assumptions. You don't give us any idea what your mechanical ability is but since you are asking I will guess it is minimal. Correct me if I am wrong.. Does it have spark? You can pull a plug wire and insert a screwdriver in the end and hold it near the engine to see if there is spark. Your model might have spark coil packs. They are harder to check and you will need some electronic equipment. If there is spark, then see if you have fuel to the injectors. Let us know the year and engine you are using.and I will try to go from there.